Loud speaker and like apparatus



Feb. 14, 1933. M, BERNARD 1,897,294

LOUD SPEAKER AND LIKE APPARATUS Filed July 30, 1931 i z E a 6 F 2 a 9 rMARCEL BERNARD- INVENTOR 2 MWLLMQ ATTOR N EYS Patented Feb. 14, 1933 i1,897,2Q4

outrun s'rarss P'rs'r MARGEL BERNARD, F PARIS, FRANCE, ASSIGN'OB I0SOCIETE FRANCAISE RADIO- ELECTBIQUE, OF PARIS, FRANCE, A CORPORATIGII 0FFRANCE LOUD SPEAKER AND LIKE APPARATUS Application filed July 30, 1931,Serial No. 553,958, and in France August 14, 1930.

The present invention relates to improve said cone 0 and coil 6 issuspended in a simiments in loud speakers and like apparatus and larmanner from the main structure or framehas for its objecttoprov'deasound-reproducwork of the apparatus (not shown). The

ing and sound-receiving device having a unirigid elements together withtheir suspensions 5 form response to applied vibratory energy aredesigned more favorably to respond to 5 over as wide a range of acousticfrequencies difierent frequency bands of vibrations which as possible.as far as possible, succeed one another with lVit-h this object in viewit is proposed in out any interruption of continuity in thefreaccordance with the present invention to emquency scale.

ploy as the vibratory element a plurality of In the embodimentillustrated in Figure 2 o conical surfaces elastically connectedtogether a single circular air-gap is provided between and driven bymeans of one or more coils imconcentric pole-pieces N, Q, A movable coilmersed in one or more circular air gaps of a B is immersed in thisair-gap and is supported magnetic circuit and traversed by alternatingin the usual manner upon a hollow tubular current-s corresponding to thesound vibramember 4 and this in turn is rigidly secured 65 tions to bereproduced or picked up. to a truncated conical membrane 01- A Anessential characteristic of the invention 0nd truncated conical membrane0 concentric resides in the fact that the coaxial conical surwi h thefirst,is connected by a flexible suspenfaces which form the vibratorysystem of the sion means S at 7 on an intermediate circle apparatus areinterconnected by elastic con- 0 the Cone 0 and at its outer peripherypro- 70 necting means which in the case of least one vided with aflexible suspension means S of the conical surfaces is attached to saidsurwhich is preferably clamped between or seface on a circle which isintermediate the incured to a pair of ring members 9 and 10 ner andouter peripheries thereof, which thus form a suspension or support forThe invention will be better understood by said cone. These ring membersmay be se- 75 reference to the accompanying drawing which ured togetherand spaced from another ring represents, by way of example only, twoparmember 11 by several tie rods or bolts 8, 8, ticular methods ofcarrying out the invenwhile a hollow magnet 6 may in turn be fas- V,tion. tened to ring member 11 of the frame thus Fig. 1 is adiagrammatical section of a loud formed. The same conditions relating tothe 80 speaker embodying the first form of the infrequency responsefavored by each diavention. phragm referred to in the description ofFig- Fig. 2 is a side section of such a loud speaker ure 1 are alsoapplicable in the present case. embodying the second form. Flgure 3shows, by way of example only, a V

Fi 31 a l i f th suspensien suspension devicePwhich may advantageousherto which the diaphragms and moving lybeemployed in connection with theparticucoils of the loud speakers may be attached. lar embodimentillustrated in Figure 2. In

In the views, the same reference indicia rethis 05186 the moving Coil BWhich in ig- 2 is fer to the same or corresponding parts. shownsupported on the hollow tubular mem- In the embodiment shown in Figure 1a. ber 4i is attached by the same to the central magnetic circuit havingconcentric poles N Q circular part a. The suspension of the coil B isprovided with two annular air-gaps 1 1 and consequently that of the cone0 which is which are likewise concentric. In the said rigidly attachedthereto is of course effected air-gaps are disposed cylindrical coils band at S on the circle 7, as already indicated, on

7J2 which are rigidly secured to truncated conithe surface of thetruncated cone 0 intermecal membranes c and 0 respectively. The diatethe ends thereof and also at the small rigid assembly comprising thecone c and its ends of the two truncated cones by the tabs X associatedcoil 5 is suspended in suitable man- (Figure 3). An annulus 7) (alsoshown on ner by means of a flexible connection from the Figure 8)supports the small end of the truncone c and the rigid assemblycomprising the cated cone C and is held by the tabs 0. As

will be obvious upon inspection of Fig. 2, magnet 6 represents themagnetic circuit, the central pole piece N having an energizing fieldcoil 5. The suspension member P may be bolted or otherwise secured inspaced manner to the pole end Q of magnet 6, if desired, by bolts orscrews such as 1, 3, the presence of the latter affording adjustment ofthe inner ends of both cones by adjustment of the suspension member P.

By suitably proportioning and otherwise providing adjustment of thesuspension members X connecting the two cones or diaphragms it will beseen that the large cone 0 can be made to respond only to the lowfrequencies and to remain substantially unaffected by high frequenciesof small amplitude. Such an arrangement results in the production of aloud speaker or electro-dynamic microphone having two ranges of responseand as compared with known apparatus having but one conicalmembra-ne ordiaphragm as at present in common use: constitutes an importantinprovement.

It is to be understood that the invention is capable of numerousmodifications other than those described and illustrated by way ofexample. p

Having now fully described my invention, I claim:

1. An acoustic apparatus comprising a support, a moving coil, means forproducing an electro-dynamic action upon said coil, a plurality oftruncated conical membranes located within the said support, saidmembraneshaving different dimensions, one of said membranes being partlycoextensive with and spaced within the other and associated with thesaid coil, elastic suspension means upon each of said membranesconnected to another element of said apparatus and elastic suspensionmeans connecting one of said membranes to the other.

2. An acoustic apparatus comprising a support, a moving coil, means forproducing an electro-dynamic action upon said coil, a plurality oftruncated conical membranes located within the said support, saidmembranes having different dimensions and facing in the same direction,one of said membranes being partly coextensive with andspaced within theother and associated with the said coil, elastic suspension means uponeach of said membranes connect-edto another element of said apparatusand elastic suspension means connecting one of said membranes toanother.

3. An acoustic apparatus comprising a support, a moving coil, means forproducing an electro-dynamic action upon said coil, a plurality oftruncated conical membranes located within the said support, said.membranes having different dimensions, one of said membranes beingpartly coextensive with and spaced within the other and associated withthe said coil and an elastic connection between the edge of a smaller toa circle on the surface or" the truncated cone of a larger membrane andintermediate the ends thereof, elastic suspension means on each of saidmembranes connected to another element of said apparatus.

4. An acoustic apparatus comprising a support, a moving coil, means forproducing an electro-dynamic action upon said coil, a plurality oftruncated conical membranes located within the said support, saidmembranes having different dimensions and being partlycoextensive andspaced apart, one of said membranes being associated with the said coil.elastic suspension means connecting one of said membranes to another,elastic suspension means connecting the large end of the largestmembrane to the support, and elastic suspension means connecting thesmall ends of the truncated conical membranes to the support, said smallends of said latter members terminating in practically the same plane.

5. An acoustic apparatus including the combination, with a support, amovable coil, means for producing an electro-dynamic action of saidcoil, of a plurality of truncated conical membranes disposed in spacedrelation and having different dimensions, one of said membranes beingpartly coextensive with another and associated with the said movablecoil, elastic suspension means connecting the larger periphery of saidone or small membrane to a larger membrane, elastic suspension meansconnecting the larger periphery of said larger membrane with thesupport, and a suspension member cut from a sheet of elastic materialinterconnecting said support and the smaller ends of the membranes.

